1. Technical Field
The present invention relates to food products. More particularly, the present invention relates to food products containing fish oils characterized by enhanced flavor stability.
2. Background Art
A great deal of attention has recently been focused on the various health benefits apparently associated with consumption of fish oil. Health benefits appear to be related to the presence of high levels of the n-3 family of polyunsaturated fatty acids. Oils containing such materials, such as fish oils, are referred to as "omega-3" oils and desirably contain high levels of n-3 fatty acids, especially eicosapentaenoic acid ("EPA") and docosahexaenoic acid ("DHA"). Such fatty acids are called "omega-3" since the first double bond occurs in the third carbon bond counting from the end or omega position of the fatty acid.
Notwithstanding the present interest in the health benefits of fish oil consumption, nonhydrogenated fish oil generally to date has not been widely used per se or as an ingredient in processed food products for use by humans due to notorious and severe problems in odor and flavor. However, gelatin capsules containing fish oil are available. Additionally, salmon oil has been added to canned salmon. Also, certain canned meat products have been marketed in Japan which have had refined fish oil added as a fortifier.
Hydrogenated fish oils are much more stable due to the decrease in the degree of polyunsaturation and are widely used in Europe for margarine. Hydrogenated fish oils have also been used in Scandinavian countries in other consumer products, e.g., cakes. Hydrogenation is also effective in reducing odor and flavor that develops in deodorized oil. However, hydrogenation by decreasing polyunsaturation including the n-3 fatty acid component correspondingly decreases the health value of fish oil. Accordingly, it would be desirable to realize a nonhydrogenated fish oil or food products containing such nonhydrogenated fish oils, but nonetheless of increased stability.
The principal approach taken in the art to utilize nonhydrogenated fish oil has been to employ fish oils of enhanced stability. Two broad approaches have been taken in the art to realize nonhydrogenated fish oils of enhanced stability. The first approach involves giving attention to the processing of the oil to achieve a cleaner, finished oil product. Particular attention has been given to the deodorization step in order to realize cleaner finished fish oil products.
In the second approach, the art has attempted to find adjuvants which can be added to finished fish oil to provide desired additional stability. For example, while the phenomenon of fishy flavor dvelopment is not completely understood, it is known, however, that oxidative rancidity is a contributing factor. Addition of known antioxidants, singly as well as commercial mixtures, some allegedly synergistic, does result in some increase in stability. However, the unstability of nonhydrogenated fish oils is so great, that even addition of such materials at maximum legally permitted levels provide only modest increases in stability.
Given the severe difficulties in realizing a suitable fish oil ingredient, it is understandable that comparatively little developmental effort has been made to formulating processed food products containing fish oil.
The prior art also includes U.S. Pat. No. 4,357,362 (issued Nov. 2, 1982 to David Barker). This patent discloses a pet food composition including fish flesh of reduced fishy odor by subjecting the composition in a sealed container, to sterilizing heat in the presence of a reducing agent. However, several disadvantages exist with this approach. First, the primary advantage is a fish odor reduction which is not necessarily directly related to the problems of fish oil flavor degradation. Second, the reduction in aroma is most likely due to the heat treatment in a sealed container. It is undesirable for many foods to be subjected to such severe heat treatment. Third, fish flesh or fish proteinaceous material, an essential ingredient of these pet foods, is known to have a material effect on oil stability. However, many food products, e.g., mayonnaise cannot contain fish flesh, yet could beneficially include fish oil were oil stability nonetheless obtained. Also, the product is less susceptible to oxidative rancidity since it is sealed. Finally, a wide variety of organic and inorganic reducing agents are taught as useful although reducing sugars are preferred.
Given the state of the art with regard to fish oil stabilization, there is a continuing need for the development of new and improved fish oil compositions and processed food products containing fish oil of improved stability.
Accordingly, it is an object of the present invention to provide nonhydrogenated fish oil and food products containing nonhydrogenated fish oils which nonetheless exhibit improved stability against degradation in both flavor and odor.
It is another object of the present invention to provide food products of enhanced stability which do not require heat sterilization.
Another object of the present invention is to provide food products containing fish oil which do not require fish meat.
Still another object of the present invention is to provide food products containing fish oil of enhanced stability against flavor degradation.
It has been most surprisingly discovered that the above objectives can be realized, that long-standing problems associated with employment of fish oils in processed foods have been addressed and food products containing fish oils can be prepared by incorporation of modest amounts of fructose. Surprisingly, fructose alone among sugars and other materials appears to be unexpectedly superior in providing the desired stabilization benefits.